论文标题
结构对巨型单极共振的影响和核不理性的确定
Structure effects on the giant monopole resonance and determinations of the nuclear incompressibility
论文作者
论文摘要
巨大的共振是集体核振动，可提供独特的实验室环境，以探测核力量的大量特性。等视压压缩模式之一 - 等构巨型单极共振（ISGMR） - 可用于约束核物质状态（EOS）方程。例如，核不可压缩性，$ k_ \ indty $是EOS中的基本数量，与有限核中ISGMR的能量直接相关。 先前的工作表明，与$ k_ \ infty $相互作用，以$^{208} $ pb和$^{90} $ zr良好地重现ISGMR的能量，高估了锡和cadmium核。为了进一步研究这种“柔软性”在远离双封闭的核$^{90} $ zr时出现的位置，以及该效果如何发展，本文的第一部分是由钼同位素中ISGMR的测量组成的。 ISGMR强度与随机相位近似计算的比较表明，这些核具有与TIN和Cadmium nuclei相似的ISGMR能量，而$^{208} $ pb的强度精确地得到了复制。这清楚地表明，钼核表现出相同的开放式柔软性，这是先前已记录的。 包括广泛的质子中性不对称的同位素中的ISGMR限制了核不可压缩性不对称性的依赖性，这是由不对称项$k_τ$量化的。为了调和先前发布的，高度关于$k_τ= + 582 $ MEV的结论，本文的第二部分集中于独立研究这一主张。 $^{40,42,42,44,48} $ ca以$^{40,42,44,48} $ ca的同时测量，排除了$k_τ$的正值的可能性，并发现与以前的数据保持一致，将$k_τ$放在$ -510 $ -510 \ pm 115 $ MEV。
Giant resonances are collective nuclear vibrations which provide a unique laboratory setting to probe the bulk properties of the nuclear force. One of the isoscalar compressional modes -- the isoscalar giant monopole resonance (ISGMR) -- is useful in constraining the equation of state (EoS) of nuclear matter. For example, the nuclear incompressibility, $K_\infty$, is a fundamental quantity in the EoS and is directly correlated with the energies of the ISGMR in finite nuclei. Previous work has shown that interactions with $K_\infty$ which reproduce the energies of the ISGMR in $^{208}$Pb and $^{90}$Zr well, overestimate those of the tin and cadmium nuclei. To further investigate where this "softness" appears in moving away from the doubly-closed nucleus $^{90}$Zr, and how this effect develops, the first portion of this thesis consists of measurements of the ISGMR in the molybdenum isotopes. Comparison of the ISGMR strengths with Random Phase Approximation calculations shows that these nuclei have ISGMR energies which are overestimated to a similar degree as seen in the tin and cadmium nuclei, while the strength of $^{208}$Pb is precisely reproduced. This suggests clearly that the molybdenum nuclei exhibit the same open-shell softness which has been documented previously. The ISGMR in isotopes encompassing a broad range of proton-neutron asymmetries constrains the dependence of the nuclear incompressibility on the isospin asymmetry, as quantified by the asymmetry term, $K_τ$. To reconcile previously-published and highly concerning conclusions that $K_τ= + 582$ MeV, the second portion of this thesis is focused upon independently studying this claim. A simultaneous measurement of the ISGMR in $^{40,42,44,48}$Ca has excluded the possibility of a positive value for $K_τ$, and found consistency with previous data, placing $K_τ$ at $-510 \pm 115$ MeV.
